Liquid crystal display

ABSTRACT

A liquid crystal display for displaying an image to be visible for a viewer, has a liquid crystal, a pair of electrodes for controlling an orientation of at least a part of the liquid crystal in accordance with an electric field between the electrodes, a light source for generating a light to be transmitted through the liquid crystal to the viewer, a pair of first and second polarizer plates, the first polarizer plate being arranged between the liquid crystal and the light source, and the second polarizer plate being arranged between the liquid crystal and the viewer, and a band-pass filter for absorbing a component of the light, a wave-length of which component is not more than 440 nm, and the band-pass filter being arranged between the light source and the viewer.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This is a continuation of U.S. application Ser. No. 09/956,138,filed Sep. 20, 2001, the subject matter of which is incorporated byreference herein.

BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT

[0002] The present invention relates to a liquid crystal display fordisplaying an image to be visible for a viewer.

[0003] JP-A-8-015697 discloses that a color toner adjuster for adjustinga color tone of a light as a back light generated by a fluorescent lightsource is arranged between the fluorescent light source and a lightguide for distributing constantly the back light over a liquid crystaldisplay panel in a STN type liquid crystal display unit.

[0004] JP-A-2000-206544 discloses that an unevenness in an image to bedisplayed is restrained by preventing a liquid crystal from beingcontaminated by a liquid crystal cell sealing resin before being cured,in an active matrix in-plain switching mode liquid crystal display inwhich a pair of comb-shaped electrodes is used.

[0005] JP-A-2000-19543 discloses a method for restraining an unevennessin an image caused by an error in dimension of electrodes.

[0006] JP-A-10-170923 discloses that a twisted connection between aliquid crystal molecule and a directing layer surface at the interfacetherebetween is made weak to decrease the unevenness in the image causedby an error in distance between substrates between which the liquidcrystal is arranged.

OBJECT AND SUMMARY OF THE INVENTION

[0007] An object of the present invention is to provide a liquid crystaldisplay for displaying an image to be visible for a viewer, in which aso-called blue fog phenomenon is restrained even when a brightness ofthe image is low. The lower a voltage for controlling an orientation ofa liquid crystal is, the higher a permeability of the liquid crystal fora blue color light is. When the voltage for controlling the orientationof the liquid crystal is close to a threshold voltage of the liquidcrystal so that a transmittance of the liquid crystal for the light islow, that is, a brightness of the display is low, a light of wave-length400-440 nm as a blue color light is more effectively transmitted throughthe liquid crystal in comparison with another light of wave-length notless than 440 nm, and a difference in brightness and a difference incolor can be clearly visible. Therefore, the so-called blue fogphenomenon occurs.

[0008] According to the invention, a liquid crystal display fordisplaying an image to be visible for a viewer, comprises, a liquidcrystal, a pair of electrodes for controlling a molecular orientation ofat least a part of the liquid crystal in accordance with an electricfield between the electrodes, a light source for generating a light tobe transmitted through the liquid crystal to the viewer, a pair of firstand second polarizer plates, the first polarizer plate being arrangedbetween the liquid crystal and the light source, and the secondpolarizer plate being arranged between the liquid crystal and theviewer, and a band-pass filter for absorbing a component of the light, awave-length of which component is not more than 440 nm, and theband-pass filter being arranged between the light source and the viewer.

[0009] Since the band-pass filter for absorbing the component of thelight, a wave-length of which component is not more than 440 nm, isarranged between the light source and the viewer, when the voltage forcontrolling the molecular orientation of the liquid crystal is close toa threshold voltage of the liquid crystal so that a transmittance of theliquid crystal for the light is low, that is, a brightness of thedisplay is low, and a light of wave-length 400-440 nm as a blue colorlight is more effectively transmitted through the liquid crystal incomparison with another light of wave-length not less than 440 nm, thelight of wave-length 400-440 nm as the blue color light is restrainedfrom reaching the viewer, so that the so-called blue fog phenomenon isprevented.

[0010] In order to generate correctly another color visible for theviewer while the so-called blue fog phenomenon is prevented, it ispreferable that a transmittance of the band-pass filter for thecomponent of wave-length not more than 440 nm is smaller than atransmittance of the band-pass filter for another component of thelight, a wave-length of which another component is not less than 450 nm,that a transmittance of the band-pass filter for the component ofwave-length 400-440 nm is smaller than a transmittance of the band-passfilter for another component of the light, a wave-length of whichanother component is not less than 450 nm, that a transmittance of theband-pass filter decreases in accordance with a decrease of awave-length of a light to be transmitted through the band-pass filterwhen the wave-length of the light to be transmitted through theband-pass filter is less than 450 nm, and/or that a transmittance of theband-pass filter decreases in accordance with a decrease of awave-length of a light to be transmitted through the band-pass filterwhen the wave-length of the light to be transmitted through theband-pass filter is 400-440 nm.

[0011] The band-pass filter may be arranged between the light source anda light guide for guiding the light from the light source to the liquidcrystal to distribute the light evenly over the liquid crystal. When adiffusing plate for distributing constantly the light over the liquidcrystal is arranged between the light guide and the liquid crystal, andthe band-pass filter may be arranged between the diffusing plate and thelight guide. The band-pass filter may be arranged on the light source.The band-pass filter may be arranged on the light guide. When the liquidcrystal display comprises a pair of first and second substrates being atleast partially transparent and the liquid crystal is arranged betweenthe first and second substrates, the band-pass filter may be arranged onat least one of the first and second substrates. The band-pass filtermay be arranged on at least one of the first and second polarizerplates. The band-pass filter is preferably arranged between the lightsource and the liquid crystal.

[0012] When the liquid crystal display comprises a color filterincluding a portion for transmitting therethrough a blue light, theportion includes an agent for absorbing the component of the light asthe band-pass filter.

[0013] The band-pass filter may be a stack of layers. The band-passfilter may be a polymer for absorbing the component of the light. Theband-pass filter may be a resin including an agent for absorbing thecomponent of the light.

[0014] The light source may include a fluorescent substance forgenerating the light. The liquid crystal and the pair of first andsecond polarizer plates may form a normally close type liquid crystaldisplay unit. A direction in which the light is transmitted in theliquid crystal may be prevented from being parallel to a direction inwhich the electric field is generated or may be transverse with respectto the direction in which the electric field is generated. The liquidcrystal and the pair of first and second polarizer plates may form asuper twisted nematic type liquid crystal display unit.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a cross-sectional view showing a liquid crystal displayof in-plane switching mode of the invention.

[0016]FIG. 2 is a schematic view showing an angular relationship amongan alignment direction of long axis of liquid crystal molecule, adirection of electric field and a polarized light transmitted axis of apolarizer plate.

[0017]FIGS. 3a-3 d are views showing a change of the alignment directionof long axis of liquid crystal molecule by the electric field.

[0018]FIGS. 4a-4 c are detailed views showing electrodes, insulatinglayers, and alignment layers.

[0019]FIG. 5 is a diagram showing a crystal liquid driving circuit.

[0020]FIG. 6 is a diagram showing a spectrum generated by a cold cathodeof narrow band light emitting type.

[0021]FIG. 7 is a diagram showing a relationship between a wave lengthof a light and a band-pass filter therefor of the invention.

[0022]FIG. 8 is a chromaticity diagram according to CIE1931 of theinternational illumination committee, showing differences in color.

[0023]FIG. 9 is an oblique projection view showing the liquid crystaldisplay of in-plane switching mode liquid crystal display apparatus ofthe invention.

[0024]FIG. 10 is a diagram showing a spectral characteristic of thenormally-close in-plane switching mode liquid crystal display.

[0025]FIG. 11 is a chromaticity diagram according to CIE1931 of theinternational illumination committee, showing differences in color.

[0026]FIG. 12 is a chromaticity diagram according to CIE1931 of theinternational illumination committee, showing differences in color.

[0027]FIG. 13 is a cross-sectional view showing a STN liquid crystaldisplay of normally close type of the invention.

[0028]FIG. 14 is a chromaticity diagram according to CIE1931 of theinternational illumination committee, showing differences in color.

[0029]FIG. 15 is a cross-sectional view showing another STN liquidcrystal display of reflection and transmission combination type of theinvention.

[0030]FIG. 16 is a cross-sectional view showing another arrangement of alight guide, a band-pass filter and a diffusion plate.

[0031]FIG. 17 is a diagram showing a relationship between a brightnessand a wave length in red, green and blue light emitting LEDs.

[0032]FIG. 18 is a diagram showing a relationship between a brightnessand a spectrum in STN liquid crystal display.

[0033]FIG. 19 is a diagram showing a relationship between a brightnessfeeling and an actual brightness or luminous intensity.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0034] In a liquid crystal display of in-plane switching mode, as shownin FIG. 1, a back-light light source unit has a light source 1, a cover2, a light guide 3, a diffusing plate 4, and a reflection plate 5. Anadhesive layer (not shown) adheres to the light guide 3 and thediffusing plate 4 to prevent a loss of light through an air between thelight guide 3 and the diffusing plate 4. A light collector sheet may bearranged between the diffusing plate 4 and a polarizer plate 12. In thisembodiment, a spectrum absorber 40 is arranged between the light source1 and the light guide 3. The spectrum absorber 40 is a band-pass filterincluding a plurality of stacks of layers for absorbing a visible lightof wavelength 400-440 nm. A liquid crystal display panel of in-planswitching mode in which an electric field applied to a liquid crystallayer 10 is substantially parallel to a substrate is used as anormally-close type liquid crystal display utilizing birefringence ofthe first embodiment. In the liquid crystal display panel, the liquidcrystal layer 10 is arranged between substrates 13 and 14, and thesubstrates 13 and 14 are arranged between the polarizer plates 11 and12.

[0035] An inner surface of the substrate 14 has stripe-shaped electrodes22 and 23, and a alignment layer 15 covering the electrodes 22 and 23.The electrode 22 is a common electrode to which a voltage ofpredetermined wave form other than an image signal voltage is applied,and the electrode 23 is an image pixel electrode to which a wave form ofvoltage changeable in accordance with the image signal is applied. Animage signal electrode 24 is arranged at the same height as the imagepixel electrode 23. An insulating layer 21 of silicon-nitride is formedbetween the electrodes. The substrate 13 has a color filter 16 formulti-color display. The color filter 16 may be formed on the substrate14 with the electrodes. The alignment layer 15 is formed by coating thesubstrate with a solution of 3% concentration poly-amicacid, baking thepoly-amicacid under 200 □ for 30 minutes to be changed to a polyimidelayer, and rubbing a surface of the polyimide layer. The alignment layer15 may be formed by being irradiated with a polarized ultraviolet rays.

[0036]FIG. 2 shows a relationship in angle among the electric field 93,a long axis 91 of liquid crystal molecule, and a polarized lighttransmitted axis 92 of the polarizer plate. The polarizing directions ofthe polarizer plates 11 and 12 are perpendicular to each other to formthe normally-close type liquid crystal display utilizing birefringence.A luminous intensity of the transmitted light is calculated by thefollowing formula wherein Δn is an anisotropy in refractive index, θ isan angle between the polarized light permeable axis and the long oreffective axis 91 of liquid crystal molecule, d_(eff) is a thickness ofthe liquid crystal layer, T₀ is a coefficient determined in accordancewith a permeability of light of the polarizer plate, and λ is a wavelength of the light to be transmitted.

T=T ₀·sin²2θ·sin²[(π·d _(eff) ·Δn)/λ]

[0037] The liquid crystal layer 10 is a nematic liquid crystal ofpositive anisotropy in dielectric constant, the anisotropy in dielectricconstant is 10.2, and the anisotropy in refractive index Δn is 0.073.

[0038] A permeability of light of the liquid crystal layer 10 is changedas shown in FIG. 3. Areas (a) and (b) show a non-energized condition,and areas (b9 and (d) show an energized condition in which the angle θbetween the long or effective axis 91 of liquid crystal molecule and thepolarized light permeable axis 92 of the polarizer plate is changed bythe electric field 93.

[0039] As shown in FIG. 4, The inner surface of the substrate 14 has thestripe-shaped electrodes 22 and 23, and the image signal electrodes 24is arranged at the same height as the electrode 23 on the inner surfaceof the substrate 14. A scanning electrode (gate wiring electrode) 25extends perpendicularly to the image signal electrodes 24. The alignmentlayer 15 is formed on the electrodes. An area on the substrate includesboth an amorphous-silicon area 101 and a TFT element 102.

[0040] As shown in FIG. 5, a liquid crystal display driver includes, forexample, a common electrode driver circuit 103, a vertical scanningsignal circuit 104, an image signal circuit 105 and an electric sourceand controller circuit 106.

[0041]FIG. 6 shows a spectrum generated by a cold cathode of narrow bandlight emitting type having a spectrum characteristic of a three bandfluorescent light source. A peak in the spectrum is generated at awave-length of 435 nm when this type fluorescent light source includingmercury for energizing phosphor is used. In order to restrain a blue fogphenomenon in the liquid crystal display, the peak in the spectrum needsto be absorbed. Therefore, the band-pass filter 40 is arranged betweenthe cold cathode of narrow band light emitting type 1 and the lightguide 3. A plurality of sets each including a low refractive indexdielectric layer such as magnesium-fluoride, silicon-oxide or the like,and a high refractive index dielectric layer such as zirconium-oxide,titanium-oxide or the like are stacked by a vapor deposition processuntil a number of layers reaches 6-20.

[0042] As shown in FIG. 7, the band-pass filter 40 absorbs effectively alight of wave-length not more than 440 nm, so that the blue fogphenomenon is restrained.

[0043] In a chromaticity diagram as shown in FIG. 8 according to CIE1931of the international illumination committee, a point A indicates to achromaticity obtained by the prior art normally-close transverseelectric field type liquid crystal display when a dark color isgenerated, and a point B indicates to a chromaticity obtained by thein-plane switching mode type liquid crystal display of the inventionwith the band-pass filter 40 when the dark color is generated. A pointA′ indicates to a chromaticity obtained by the prior art normally-closein-plane switching mode liquid crystal display when a bright color isgenerated, and a point B′ indicates to a chromaticity obtained by thein-plane switching mode liquid crystal display of the invention with theband-pass filter 40 when the bright color is generated. A point xindicates to a chromaticity of sun-light. An area of relatively smallvalues of x and y corresponds to a relatively blue color, and an area ofrelatively large values of x and y corresponds to a relatively yellowcolor. The point A shows that the prior art normally-close transverseelectric field type liquid crystal display emphasizes strongly the bluecolor, and the point B shows that the invention restrains the blue colorfrom being emphasized. The points A′ and B′ show that the chromaticityby the transverse electric field type liquid crystal display of theinvention and the prior art normally-close in-plane switching mode typeliquid crystal display are not different largely from each other whenthe bright color is generated. Therefore, the transverse electric fieldtype liquid crystal display of the invention with the band-pass filter40 restrains only the blue fog phenomenon, but does not have a largeinfluence for the bright color indication. The band-pass filter 40absorbs strongly the light of wave-length not more than 440 nm, butrestrains the light of wave-length preferably more than 440 nm orpractically not less than 450 nm from being absorbed strongly by theband-pass filter 40.

[0044] As shown in FIG. 9, the light sources 1 are arranged atrespective sides of a lower case 63 with an inverter drive circuit 64.The reflecting plate 5, the light guide 4, the diffusion plate 4 and theliquid crystal display panel 70 are mounted on the lower case 63. Anupper side of the lower case 63 is covered by a shield case 61 having adisplay window.

[0045] The light of wave-length not more than 440 nm does not have alarge influence for brightness. On the other hand, a permeability of thelight of wave-length 400-440 nm is high when a brightness of thenormally-close in-plane switching mode liquid crystal display is low,and is low when a brightness of the normally-close in-plane switchingmode liquid crystal display is high. Therefore, the blue fog phenomenonoccurs and the brightness of display is not changed largely by the lightof wave-length not more than 440 nm when brightness of thenormally-close in-plane switching mode liquid crystal display is low,and the brightness of display is not changed largely by the light ofwave-length not more than 440 nm when brightness of the normally-closein-plane switching mode liquid crystal display is high.

[0046] In FIG. 10 showing a spectral characteristic of thenormally-close transverse electric field type liquid crystal display, athick line 81 shows that a permeability of the light of wave-length notmore than 440 nm is high and the permeability of the light decreases inaccordance with an increase of the wave-length when the brightness issmall, and a thin line 82 shows that a permeability of the light ofwave-length not more than 440 nm is low and the permeability of thelight increases in accordance with an increase of the wave-length whenthe brightness is high.

[0047] In a chromaticity diagram according to CIE1931 of theinternational illumination committee, as shown in FIG. 11, a point Haindicating a chromaticity obtained by the normally-close in-planeswitching mode liquid crystal display including the band-pass filter 40absorbing strongly the light of wave-length not more than 430 nm whenthe dark color is generated is not different largely from the point Aindicating the chromaticity obtained by the prior art normally-closetransverse electric field type liquid crystal display when the darkcolor is generated. Therefore, the normally-close transverse electricfield type liquid crystal display including the band-pass filter 40absorbing strongly the light of wave-length not more than 430 nm cannotrestrain effectively the blue fog phenomenon. A point Hob indicating achromaticity obtained by the normally-close transverse electric fieldtype liquid crystal display including the band-pass filter 40 absorbingstrongly the light of wave-length not more than 430 nm when the brightcolor is generated is not different largely from the point A′ indicatingthe chromaticity obtained by the prior art normally-close transverseelectric field type liquid crystal display when the bright color isgenerated.

[0048] In a chromaticity diagram according to CIE1931 of theinternational illumination committee, as shown in FIG. 12, a point Chiindicating a chromaticity obtained by the normally-close transverseelectric field type liquid crystal display including the band-passfilter 40 absorbing strongly the light of wave-length not more than 450nm when the dark color is generated is different largely from the pointA indicating the chromaticity obtained by the prior art normally-closetransverse electric field type liquid crystal display when the darkcolor is generated. Therefore, the normally-close transverse electricfield type liquid crystal display including the band-pass filter 40absorbing strongly the light of wave-length not more than 450 nm canrestrain effectively the blue fog phenomenon. On the other hand, a pointHad indicating a chromaticity obtained by the normally-close transverseelectric field type liquid crystal display including the band-passfilter 40 absorbing strongly the light of wave-length not more than 450nm when the bright color is generated is different largely from thepoint A′ indicating the chromaticity obtained by the prior artnormally-close transverse electric field type liquid crystal displaywhen the bright color is generated. Therefore, yellow is emphasized inthe bright color.

[0049] As shown in FIG. 13, a normally close STN type liquid crystaldisplay has a transparent Y electrode on the transparent substrate 13, atransparent X electrode on the transparent substrate 14, the colorfilter 16, a black matrix 17 and a flattening layer 18. Each of thetransparent substrates 13 and 14 between which the liquid crystal 10 isarranged has the directing layer 15 of polyimide whose surface istreated by rubbing. The X and Y electrodes are energized by a driver(not shown). The polarizer plate 11 and a phase plate 33 ofpolycarbonate are arranged at an outside of the transparent substrate13, and the polarizer plate 12 and a phase plate 34 of polycarbonate arearranged at an outside of the transparent substrate 14. The phase plate34 may be arranged between the polarizer plate 11 and the phase plate 33or between the substrate 13 and the phase plate 33. The liquid crystallayer 10 of thickness 6.2 am is a nematic liquid crystal of positiveanisotropy in dielectric constant, and the anisotropy in refractiveindex Δn is 0.144. The nematic liquid crystal includes a choral agent(such as S811 of Merc Inc.,) to have a twist angle of 240 degrees.

[0050] In this case, an azimuth angle of the polarizing axis of thelower polarizer plate 12 is 10 degrees, an azimuth angle of thepolarizing axis of the upper polarizer plate 11 is 80 degrees, anazimuth angle of slow axis of the lower phase plate 34 is 110 degrees,an azimuth angle of slow axis of the upper phase plate 33 is 70 degrees,and retardations of the phase plates 33 and 34 are 400 nm. The azimuthangles are set in such a manner that the twist angle is 240 degrees, andrubbed angles of the upper and lower directing layers are ±30 degreeswith respect to a longitudinal direction of the liquid crystal displaypanel. The arrangement of the light source unit and the band-pass filter40 is the same as the embodiment shown in FIG. 1.

[0051] In a chromaticity diagram according to CIE1931 of theinternational illumination committee, as shown in FIG. 14, the band-passfilter 40 restrains the blue fog phenomenon in the normally close STNtype liquid crystal display.

[0052] As shown in FIG. 15, a reflection and transmission combinationSTN type liquid crystal display panel has a transmission area formed bya transparent electrode 31 of, for example, ITO, and a reflection areaformed by a reflection electrode 51 of, for example, aluminum in eachpixel on the substrate 14. When the electrodes are formed on thesubstrate, a transparent electrode layer of, for example, ITO isdeposited by sputtering process on the transparent substrate 14, and apart of the transparent electrode layer is removed to form a pattern ofthe transparent electrode layer as the transparent electrode 31.Subsequently, a reflection electrode layer of, for example, aluminum isdeposited thereon, and a part of the reflection electrode layer isremoved to form a pattern of the reflection electrode layer as thereflection electrode 52. The color filter (not shown) is formed on thesubstrate.

[0053] When this reflection and transmission combination STN type liquidcrystal display panel is used with the light source unit and theband-pass filter 40 as described above, the blue fog phenomenon is alsorestrained effectively. The reflection electrode may be formed on thetransparent electrode. The transparent electrode and the reflectionelectrode may be driven electrically independently of each other.

[0054] As shown in FIG. 16, a band-pass filter 41 having the sameabsorption characteristic for the light as the band-pass filter 40 maybe arranged between the light guide 3 and the diffusing plate 4. Thefluorescent light source 1 may be arranged under the light guide 3.

[0055] An acrylic type polymer layer including cyano-acrylate absorbentmay be used as the band-pass filters 40 and 41. The acrylic type polymerlayer including cyano-acrylate absorbent may be formed on the lightguide 3 by coating a rotated surface of the light guide 3 with theacrylic type polymer layer of monomer condition including cyano-acrylateabsorbent, and polymerizing the acrylic type polymer layer of monomercondition including cyano-acrylate absorbent on the surface of the lightguide 3. The cyano-acrylate absorbent absorbs effectively the light ofwave-length 400-440 nm. The acrylic type polymer layer includingcyano-acrylate absorbent may be arranged directly on the three bandfluorescent light source 1 or LED. The band-pass filters 40 or 41 may bearranged directly on the three band fluorescent light source 1 or LED.The light source may be formed by a combination of monochromatic red,green blue LEDs.

[0056] As shown in FIG. 17, the blue LED generates the light ofwave-length 450-480 nm, the green LED generates the light of wave-length520-570 nm, and the red LED generates the light of wave-length 600-660nm. An extremely small amount of light of wave-length not more than 440nm is absorbed by the band-pass filters 40 and 41 between the lightguide 3 and the diffusing plate 4 to restrain the blue fog phenomenon.

[0057] The cyano-acrylate absorbent absorbing effectively the light ofwave-length 400-440 nm may be included by the adhesive between thepolarizer plate 12 and the phase plate 51 shown in FIG. 15. In thiscase, the diffusing plate 4 is not necessary.

[0058] The acrylic type polymer layer including cyano-acrylate absorbentabsorbing effectively the light of wave-length 400-440 nm may bearranged on the substrate 13. The band-pass filters 40 or 41 or theabsorbent absorbing effectively the light of wave-length 400-440 nm maybe arranged between the liquid crystal display panel and a viewer of theliquid crystal display. The color filter may includes the absorbentabsorbing effectively the light of wave-length 400-440 nm. The absorbentabsorbing effectively the light of wave-length may be included by a bluecolor filter or an overcoat layer of the color filter.

What is claimed is:
 1. A liquid crystal display for displaying an imageto be visible for a viewer, comprising, a liquid crystal, a pair ofelectrodes for controlling an orientation of at least a part of theliquid crystal in accordance with an electric field between theelectrodes, a light source for generating a light to be transmittedthrough the liquid crystal to the viewer, a pair of first and secondpolarizer plates, the first polarizer plate being arranged between theliquid crystal and the light source, and the second polarizer platebeing arranged between the liquid crystal and the viewer, and aband-pass filter for absorbing a component of the light, a wave-lengthof which component is not more than 440 nm, and the band-pass filterbeing arranged between the light source and the viewer.
 2. A liquidcrystal display according to claim 1, further comprising a light guidefor guiding the light from the light source to the liquid crystal,wherein the band-pass filter is arranged between the light source andthe light guide.
 3. A liquid crystal display according to claim 1,further comprising a light guide for guiding the light from the lightsource, and a diffusing plate for distributing constantly the light overthe liquid crystal, wherein the diffusing plate is arranged between thelight guide and the liquid crystal, and the band-pass filter is arrangedbetween the diffusing plate and the light guide.
 4. A liquid crystaldisplay according to claim 1, wherein the band-pass filter is arrangedon the light source.
 5. A liquid crystal display according to claim 1,further comprising a light guide for guiding the light from the lightsource to the liquid crystal, wherein the band-pass filter is arrangedon the light guide.
 6. A liquid crystal display according to claim 1,further comprising a pair of a first substrate being transparent and asecond substrate being at least partially transparent, wherein theliquid crystal is arranged between the first and second substrates, theband-pass filter is arranged on at least one of the first and secondsubstrates.
 7. A liquid crystal display according to claim 2, furthercomprising a color filter including a portion for transmittingtherethrough a blue light, wherein the portion includes an agent forabsorbing the component of the light as the band-pass filter.
 8. Aliquid crystal display according to claim 1, wherein the band-passfilter is arranged on at least one of the first and second polarizerplates.
 9. A liquid crystal display according to claim 1, wherein theband-pass filter is a stack of layers.
 10. A liquid crystal displayaccording to claim 1, wherein the band-pass filter is a polymer forabsorbing the component of the light.
 11. A liquid crystal displayaccording to claim 1, wherein the band-pass filter is a resin includingan agent for absorbing the component of the light.
 12. A liquid crystaldisplay according to claim 1, wherein the light source includes afluorescent substance for generating the light.
 13. A liquid crystaldisplay according to claim 1, wherein the liquid crystal and the pair offirst and second polarizer plates forms a normally close type liquidcrystal display unit.
 14. A liquid crystal display according to claim 2,wherein a direction in which the light is transmitted in the liquidcrystal is transverse with respect to a direction in which the electricfield is generated.
 15. A liquid crystal display according to claim 2,wherein the liquid crystal and the pair of first and second polarizerplates forms a super twisted nematic type liquid crystal display unit.16. A liquid crystal display according to claim 1, wherein the band-passfilter is arranged between the light source and the liquid crystal.